Double signal system



M. w. MUEHTER DOUBLE SIGNAL SYSTEM Jline 39; 1942.

Filed July 12, 1938 9 0 M 5 r 7 V J 5 3 8 4 L i v a, n 7 vg M"Y\5 INVENTOR M.W. MUEHTER BY $4M ATTORNEY Patented June 30, 1942 7 DOUBLE SIGNAL SYSTEM Manfred W. Muehten'Nutlcy, N. J., assignor to American District Telegraph Company, New York, N. Y., a corporation of- New Jersey Application July 12, 1938, Serial No. 218,795

11 Claims.

This invention pertains to signal systems generally and more particularly to signal systems of the type used for supervising watchmans tours or for fire alarm circuits or other circuits used in a supervisory sense. It is desirable in these particular applications that signals should be received during abnormal conditions of the signaling circuit, such as grounded transmitters, grounded line or shorted transmitters and shorted lines, and even direct short-circuits across the circuit at the central oifice. The system embodying this invention is similar to the well known McCulloh system wherein the circuit can be changed for the purpose of receiving the signals during the above-mentioned abnormal conditions except that the circuit contains refinements which provide for more efficient operation under McCulloh conditions and further provides for non-interfering simultaneous transmission of signals from two transmitters on the same circuit.

The primary object of this invention is to provide a signal circuit of the type mentioned above for accomplishing the results and overcoming the difficulties and abnormal conditions mentioned above.

Another object of this invention is to provide an improved signal system wherein two transmitters on the same circuit may simultaneously transmit signals without interfering with one another. 1

A- further object of this invention is to provide a signal system wherein two transmitting sta-v tions are arranged to be non-interfering and to simultaneously transmit signals to the central station where the signals may be simultaneously recorded on either a double pen register or on two separate registers.

Another object of this invention is to provide a signal system of the McCulloh type wherein two signal boxes .on the same transmission line may simultaneously transmit signals over different sides of the same line circuit.

A still further object of this invention is to provide for nonnterfering simultaneous trans mission of two box signals on the same circuit and to further provide a differential relay for controlling the central office circuit under both normal and abnormal conditions of the circuit.

A further object of the invention is to provide a double-signal McCulloh system which includes means for accomplishing non-interfering simultaneous transmission of two box signals over the same circuit and automatic means for changing the central ofiice circuit to provide McCulloh operation.

This system is of the double-signal McCulloh type which provides for non-interfering simultaneous transmission of signals from at least two boxes onthe same circuit. The system also includes two recorders or a double pen register for each circuit. If only one box or transmitter is operated, the signal will be recorded by both registers or both pens of a double pen register whereas if two transmitters are operated at the same time one' pen will record one signal and the other pen will record the second signal. If more than two transmitters are operated simultaneously the two transmitters located nearest to the two ends of the circuit will operate the recorders while the other transmitters will be prevented from interfering. Unless the signals completely overlap, part of the signals will be received before or after the transmission of the signals by the transmitters located nearest to the ends of the line. The transmitters are .of the conventional type and are arranged so that ground is not ordinarily connected to the code "eration during abnormal conditions of the line circuit such as grounded transmitters, grounded transmission line or short-circuits in the circuit, even short-circults across the line itself.

The foregoing and more specific objects will appear from the following complete disclosure of the invention.

The drawing shows a circuit diagram of a system embodying the invention.

In general, the drawing shows a line circuit including a plurality of transmitters I, II and III arranged in series relation, a line relay l5 and a differential relay or ground relay I E], both arranged in series relation to the transmission line. The line relay l5 and the ground relay l0 control relays 25, 39, 40 and 10 which in turn control theregisters 50 and '69. Battery 28 is common to the whole circuit "but, isshown connected at different points inthe, circuit in order to. avoid complication of the drawing,

For the normal line condition, the supervisory circuit can be traced from battery 20 through the right hand winding of relay It], a line compensating resistor 6, the out jack, the line circuit including the boxes I, II and III, the in jack, the right hand winding I! of line relay l5, break contact 43 of main switching relay 40 and. the left hand winding H of relay It to ground. Since the windings H and 12 of the relay Ill are equal and opposing, this relay is normally deenergized and relay I5 is normally energized by the supervisory current. The impulse limiting relay 25 is normally energized from battery 20 through back contact I3 of relay l0.

When a box or transmitter is operated, a break impulse is transmitted due to the opening of the line circuit by the spring 2 for instance, which is operated by the code wheel thereby causing the line relay E5 to release. This closes a circuit from battery 26. through back contact l3 of ground pulse, the pen spring l closes to prepare the circuit for the ground signal. Ground relay in is energized when the code contacts close, from battery 23 through winding I2, the winding ll being shunted by ground. The armature of ground relay l closes the make contact to energize the main switching relay 40 through the left-hand normally closed switch contact of switch 39 and winding 4| to ground. Another circuit can be traced from battery 20 through the make contact l3 of ground relay I0 through conductor 14, through contact 34 of impulse limiting relay 38, through conductor 35, contact 21 of impulse limiting relay 25, series resistor 49 and register 50 to ground, thereby causing the first impulse to be recorded. As impulse limiting relays 25 and 33 are of the slow release type, their armatures remain operated for a certain length of time, even though the circuit is opened at the back contact of ground relay l0. Switching relay Llfi operates to disconnect the line relay I5 from the left hand winding ll of ground relay l0 and connect it through a compensating resistance l to battery 20 and ground by means of contact 53. Since at this time ground is connected to the line by the transmitter, line relay l5 operates and energizes the other register 60 through a circuit which can be traced from battery 20 through make contact 44, contact I8 of relay [5, contact 33 of relay 30, make contact 48 of relay 4E3, compensating resistance 59 through the register 69 to ground. In order 'to speed up the response of line relay l5 to the ground impulse, this relay is provided with a second winding H; which is energized in multiple with the circuit of the ground register 59 through contact 46 of relay 40 until main switching relay 40 picks up. At that time a circuit is also closed for auxiliary switching relay 10 which can be traced from battery through contacts 44 and 44 of relay 48, contact 32 of relay 33 and winding H of relay 10 to ground. Auxiliary switching relay [0 picks up and closes a locking circuit through its right hand contact l4 and make contact 3! of relay 3!) to battery, and contacts 14 also bridge contact 32, thereby preventing auxiliary switching relay 1!] from releasing until both relays 33 and All are deenergized. The following break impulse causes relays l0 and IE to deenergize resulting in a space on the recorder tape. The circuit of relay 40 is interrupted at this time but since it is of the slow release type it will not release its armature during the transmission of break impulses. At the time of the transmission of break impulses, relays and 3b are again energized. After the first break impulse, however, the circuit for relay 33 is changed due to the operation of relays 4i and 10 causing it to be energized in a circuit which can be traced from plus through make contact at of relay 45, break contact l8 of relay l4, make contact (3' of relay 10 through the relay to ground. Relays l0 and I5 are energized after each break impulse of the transmitter causing the two register circuits to be energized and to record impulses on the tape. At the end of a digit, the register circuits would be energized for the whole time of the interval until the first break impulse of the succeeding digit, but for the action of impulse limiting relays 25 and 30 which release after a short delay, cutting or limiting the recording impulse to its normal length, this also being true tor the ground condition following the transmission of the last break impulse of the signal.

The ground contact I of the transmitter stays closed as long as the transmitter is running. When the transmitter finally removes the ground connection from the line, relays l3 and i5 drop out and stay deenergized, causing main switching relay it to release after a certain time. This relay restores its contacts to the normal condition, relay i5 picks up again through the normal line circuit opening the circuit of impulse limiting relay 30 at break contact l8 (relay 33 had been energized at the time line relay I5 released upon removal of the ground from the line circuit). The closure of make contact I8 however does not cause another impulse to be recorded on register 60 since make contact 48 and contact 15 are both open. When impulse limiting relay 30 releases after a short interval of time, armature 3! drops and as contact 44 is already open, relay H1 is released. Contact 75 closes but contact 33 being open the register circuit of register 60 is still open. Everything is now in normal condition again.

If two or more transmitters are operated simultaneously, the circuit will function in substantially the same manner as described above. However, the two transmitters located nearest to the ends of the line will transmit their signals to the register magnets respectively without interfering with one another and without being interfered with by additional boxes between them that may be operating at the same time since the line beyond the box nearest to either side of the circuit will always be either open or grounded. Consequently, whatever signal is put on the line beyond this box will have no efiect. When two transmitters operate simultaneously one will operate the ground relay III which controls the register 53 through a circuit from battery 20, contact l3, line Hi, contact 34 or 16, line 35, contact 21, resistor 39 to register 56. The transmitter at the other end of the line will control register 60 through a circuit which can be traced from battery 20, contact 44, make contact 40, make contact i8 of line relay !5, contact 33, make contact 48, resistor 59 to recorder 60 and ground, as explained above.

If two signals are being transmitted, one of them may be .broken :up if a third transmitter nearer to zthenofiice on the-line circuitis started. However, this third signal will be transmitted Without interference.

It may appear that since the circuit is thrown to the McCulloh condition during the transmis sion of a signal, 'thatground at the box'is essentialafor the transmission of a signal. However, this is. onlyitrue so far as the-non-interference "feature is concerned. If the ground connection ofa transmitter .becomes defective for some rearson,the..operation of thexcircuitwillbe slightly different. During the transmission of the first breakimpulse by:the code-wheel 2, impulse'limiting .relay 130 will again be energized as .-explained above. .Atthe'termination of the break impulse :theline circuit is closed againyandgline relay I15 picks.up to record theimpulseyon ;the associated register 65 through a circuit which can be traced from battery .20 through contact |.3,'Iback contact-40f, makecontacts i8, and 33, .baCkcontacts Hand 15,,series resistor 59 and register. 60 to ground. .As ground relay is not operated .at this time, switching relays 40 and 70 likewise fail "to operate. The line circuit remains in a normal condition and the signal is only recorded on the side of .the register associated .with.:line relay 15. .This is an indication -:to..the:operator ofa trouble condition at the particular transmitter. Thistrouble condition may also be .a shunt across the box .as will be explained .below. Even if the ground connection to.a..transmit.tershould; become faulty during the -.transmission of..-a. normalsignal, the circuit .will -be automatically conditioned ,to properly receive -the;.remainder. of thesignal. It willube recalled that during the transmission ofanormal signal, theiline circuit is thrown intotheMcCulloh con- .dition and signals .are transmitted through :ground. 'In ,case .thisground connection. should :become; faultyduring theoperation ofzthe transmitter,=-re1ays; l0. and. 1.5 .will drop :outimmediately and stay deenergized, but after ashortiniterval oft.time,-switching relays-40 releases,.restorling; theiline circuitto the. normal condition and .-permitting...the .ilinerelay...l.51.to' follow; the .break .impulses andzto record; the signal on thetape .as :soon. as .relay, fill is ideenergized. .This .occurs -upon -the.release voi" relay..3i1 during .the. first ilonger. spacezbetween breakimpulsesor; even on .thefirstspace, if thebqx'iszfairly slow.

.rIn' caseithetransmitter. contacts become. shortcircuited,. or..if ..the..entire loops-becomes .shortcircuited:;for. .some 1. reason,...a :signal can still. be sent fromthe particular .transmitter :or; transimittersinvolyed. ..In thiscase no. break impulse is transmitted when the pen contacts .of;th.e box .open. the; first time. .However, sincetheeround connection :is; established .at gthis time, ground .2 reclose and. energizes-relay. winding ,4 Lof. main switching...r.el ay ddthroughconductor l4,and;the

i$ Q ;i$; !l by a circ it which anzbe aced ro at e .20 throu h mak cor.1itacts 44, k8, A1, and contact ;'|5 to register ,60 a d oun r ordinaanimpuise o t e tap uxi yaw h nere a 7 f l t ickup sin line -relay 15 ;-failed to release and energize impulse ;li-miting relay 30 leaving contact '32 open. In-this-case relay- 2 5 acts-as the impulse limiting relay ,for register -60-by;rneans of 7 its con-tactZB. When; during the-following break impulse, (relays 10 and 1-5 are deenergizedrelay 39 again :fails to operate since its circuit is open at the break contact 45'. Thedollowing ground impulse is again recorded on the register associated with the armatureof line relay -15 as described above. As in .the case of a signal from a transmitter with a faultyground connection, the signal is again recorded on only one side of theregister thus giving an indication of a trouble condition and in this particular case a shunt condition on the line.

In case of a leakageiconolition on the line that is not of sufficient intensity to'givenan indication byoperating the differential ground relay {0, all transmitters will still beable to transmit asignal providing that there is a leakage on only one side of the transmitter. Line relay l5 will respond to the f rst break impulse and energize impulse limiting, r lay 30 through -a circuit which can ice-traced from battery 329 through back contacts I3, 45, L8, '13, and 4 5 and relay ..3.0 to r und- G und c l0 .wil 'als operate as n a e fo lowing ro nd mpu1s.e is t ansmitted and cause main switching relay .40 to operate. Tfhis relay, as previously, throwsthe circuit to the McCulloh condition and also causes auxiliary switching relay 10 to pick up. If the transmitter is located between the leakage and the a .I5.. e a .lflma then main ener ized throughlthe leakage, independently of the transmitter, and the signal will be recorded by the line relay I 5 -followingth e code.

If the box is'located between sufficient leakage and the ground-relay I 0, the line relay l5 will not follow the conditionbut will hold up through the leakage after the first ground impulse has been made. The ground relay Ill, however, will follow the code.

In case relay It] or I5, or both, remain energized through'the leakage at the end of thesignal, main switching relay 45 will also remain energized. Relay 4!] is provided with a locking Winding 42 for holding this relay energizedin case line relay l5 should remain energized at the end of the signal, but notground relay II]. This locking circuit can be traced from battery 20 through make contacts Mi, l8 and 41 and winding 42 to ground. An indication of trouble is obtained bythe lighting of the trouble lamp 5| which is energized from battery through make contacts 44, 44', back contact 3| or from battery through make contact 3|, then through resistance 52, lamp 5!, through right-hand normally closed contact of the switch 39 through the common trouble relay 55 to ground, thereby advising the operator of the trouble condition.

In case of a ground sufiicient to operate the ground ,relay l5, an indication is given through the trouble lamp circuit as traced above, through makecontacts 44, 44 and back contact 3l'. The operator throws the McCulloh conditioning switch 39, which takes the trouble lamp circuit off; the trouble relay and connects it directlyto ground as shown in the drawing. Ifhe other zb adfiQf th -sw c nn t wind n M main switching relay 40 in series with winding 12 of auxiliary switching relay (0, thereby energizing both relays 40 and HI; relay 40 throws the line circuit to the McCulloh condition. The same is true in case of a break, except that the trouble lamp circuit in this case is closed through make contact 3|, relay 30 picking up when the armature of relay I releases to close the break contact. In either case, signals on either side of the trouble can still be transmitted, since either of the relays It] or 15 will follow the impulses and operate the corresponding register.

It will be apparent from the foregoing description that I have devised a novel non-interfering,

simultaneous double signal McCulloh system.

The present invention is susceptible of various modifications within the scope of the appended claims which will be obvious to those skilled in the art.

I claim:

1. In a signalling system, a transmission line, a plurality of stations connected in said line, a relay responsive to ground impulses connected to one end of said line, another relay responsive to breaks in said line and connected to the other end of said line, a switching relay energized by contacts of said first relay for energizing said second relay through ground whereby said second relay responds to ground signals, a recorder and switching means controlled by said main switching means for connecting said recorder to contacts of said second relay whereby the ground signals are recorded during short-circuits of said line or said stations.

2. In a signal system, a transmission line, a plurality of transmitting stations connected in series in said transmission line for transmitting break and ground signals, a grounded source of potential, a difierential relay connected in series with said line, one coil of which is connected between one end of said line and said source whereby it is energized by ground signals to operate the relay, the second coil of which is connected to the other end of said line and ground whereby it may be shunted by ground at the stations, said coils normally being energized to balance one another whereby line leakage does not cause false signals, a line relay connected in series in said transmission line and with the second coil of said differential relay whereby the line relay is responsive to break signals, a slow to release main switching relay operated by said differential relay for disconnecting the second coil of the differential relay and connecting said line relay coil to battery whereby it is energized by ground signals, a slow to release auxiliary switching relay energized by said line relay in response to the first break signal, a recorder connected by said switching relays. to contacts of said line relay for recording signals from one side of the line and another recorder connected to contacts of said differential. relay by said auxiliary switching relay for recording signals from the other side of the line: whereby signals from two separate transmitters may be received and recorded simultaneously,

3. In a signal system, a transmission line, a plurality of transmitting stations connected in series in said transmission line for transmitting; break and ground signals, a grounded source of potential, a differential relay connected in series, with said line, one coil of which is connected between said line and said source whereby it is. energized by ground signals, the second coil of which is connected to the other end of said line and ground, said coils normally being energized to balance one another, a line relay connected in serie in said transmission line whereby the line relay is responsive to break signals, a switching relay operated by said differential relay for disconnecting the second coil of the differential relay and connecting said line relay coil to battery whereby it is energized by ground signals, a recorder controlled by the line relay for recording signal from one side of the line and another recorder controlled by the differential relay for recording signals from the other side of the line whereby signals from two separate transmitters may be received and recorded simultaneously.

4. In a signal system, a transmission line, a plurality of transmitting stations connected in said transmission line for transmitting break and ground signals, a grounded source of potential, a differential relay connected in series with said line, one coil of which is connected between one end of said line and said source whereby it is energized by ground signals, the second coil of which is connected to the other end of said line and ground, said coils normally being energized to balance one another whereby line leakage does not disable the system, a line relay connected in series in said transmission line and with the second coil of said differential relay whereby the line relay is responsive to break signals, a main switching relay operated by said differential relay for disconnecting the second coil of the differential relay and connecting said line relay coil to battery whereby it is energized by ground signals, an auxiliary switching relay energized by said line relay, a recorder connected by said switching relays to be controlled by said line relay for recording signals from one side of the line and another recorder connected by the auxiliary relay to be controlled by said diflerential relay for recording signals from the other side of the line whereby signals from the two separate transmitters may be received and recorded simultaneously.

5. In a signal system, a transmission line, a plurality of transmitting stations connected in .series in said transmission line for transmitting break and ground signals, a grounded source of potential and a differential relay connected in series with said line, one coil of which is connected between one end of said line and said source whereby it is energized by ground signals, the second coil of which is connected to the other end of said line and ground, said coils normally being energized to balance one another but becoming unbalanced during certain leakage conditions whereby break signals may be repeated .by said relay.

6. In a signal system, a transmission line, a plurality of transmitting stations connected in series in said transmission line for transmitting break and ground signals, a grounded source of potential, a difierential signal repeating relay connected in series with said line, one coil of which is connected between one end of said line and said source to operate the relay, the second coil of which is connected to the other end of said line and ground, said coils normally being energized to balance one another and a line signal repeating relay connected in series in said :transmission line and with the second coil of said :differential relay.

'7. In a signal system, a transmission line, a plurality of transmitting stations connected in series in said transmission line for transmitting .break and ground signals, a grounded source of potential, a differential relay connected in series with said line, one coil of which is connected between one end of said line and said source whereby it is energized by ground signals to operate the relay, the second coil of which is connected to the other end of said line and ground whereby it may be shunted by ground at the stations, said coils normally being energized to balance one another whereby line leakage does not cause false signals, a line relay connected in series in said transmission line and with the second coil of said differential relay whereby the line relay is responsive to break signals and a main switching relay operated by said differential relay for disconnecting the second coil of the difierential relay and connecting said line relay coil to battery whereby it is energized by ground signals.

8. In combination, a transmission circuit comprising a transmission line, a grounded source of potential connected to one 'end thereof, a plurality of transmitters in said line, each of which comprises a contact for continuously grounding the line during transmission of each digit and other contacts for breaking the line in accordance with the code, a signal repeating means comprising a differential relay, one coil of which is connected between one end of said line and said source of potential whereby it can respond to ground signals originating in the portion of the line between itself and a line break or to signals from a shunted transmitter, the other coil of which is connected between the other end of said line and ground whereby it can respond to signals originating on the other side of said line, and a line relay connected in said other side of the line and responsive to normal signals therein or to line make and break signals in the absence of ground at one or more transmitters and circuit converting means comprising transfer contacts in the line between the line relay and the difierential relay, one of which is normally closed to the differential relay and the other of which is normally open and connected to the grounded source of potential and a relay connected to contacts of the differential relay and operated by it for operating the transfer contacts to disconnect the differential relay from the line relay and connect the source of potential to the line relay whereby it may repeat signals from one side of the line and the differential relay may repeat signals from the other side of the line.

9. In combination, a transmisison circuit comprising a transmission line, a grounded source of potential connected to one end thereof, a plurality of transmitters in said line, each of which comprises a contact for continuously grounding the line during transmission of each digit and other contacts for breaking the line in accordance with the code, a signal repeating means comprising a differential relay, one coil of which is connected between one end of said line and said source of potential whereby it can respond to ground signals originating in the portion of the line between itself and a line break or to signals from a shunted transmitter or several of them, the other coil of which is connected between the other end of said line and ground whereby it can respond to signals originating on the other side of said line, and a line relay connected in said other side of the line and responsive to normal signals therein or to line make and break signals in the absence of ground at one or more transmitters and circuit converting means comprising a switch operated by the differential relay for disconnecting the differential relay from the line relay and connecting the source of potential to the line relay whereby the line relay may repeat signals from one side of the line and the differential relay ma repeat signals from the other side of the line.

10. In combination, a transmission circuit comprising a transmission line, a grounded source of potential connected therein, a plurality of transmitters in said line, each of which continuously grounds the line during transmission of each digit and breaks the line in accordance with the code, a signal repeating means comprising one coil which is connected between one end of said line and said source of potential whereby it can respond to ground signals originating in the portion of the line between itself and a line break or to signals from a shunted transmitter, and another coil which is connected between the other end of said line and ground whereby it can respond to signals originating on the other side of said line, and a line relay connected in said other side of the line and responsive to normal signals therein or to line make and break signals in the absence of ground at one or more transmitters.

11. In combination, a transmission circuit comprising a transmission line, a grounded source of potential connected to one end thereof, a plurality of transmitters in said line, each of which comprises a contact for continuously grounding the line during transmission of each digit and other contacts for breaking the line in accordance with the code, a signal repeating means comprising a differential relay, one coil of which is connected between one end of said line and said source of potential whereby it can respond to ground signals originating in the portion of the line between itself and a line break or to signals from a shunted transmitter, the other coil of which is connected between the other end of said line and ground whereby it can respond to signals originating on the other side of said line, and a line relay connected in said other side of the line and responsive to normal signals therein or to line make and break signals in the absence of ground at one or more transmitters.

MANFRED W. MUEHTER. 

